37,627 research outputs found
Effects of growth factors and receptor blockade on gastrointestinal cancer
The advent of recombinant peptide technology offers the potential to use one or several peptides to treat a variety of gastrointestinal conditions. However, although cell culture and animal models have shown proof of concept, we are still at a relatively early stage in translating their use to standard clinical practice. Similarly, peptide and non-peptide antagonists of growth factor receptors show great potential as novel antichemotherapy agents. However, their actual place in clinical practice has yet to be established
Single photons from a gain medium below threshold
The emission from a nonlinear photonic mode coupled weakly to a gain medium
operating below threshold is predicted to exhibit antibunching. In the steady
state regime, analytical solutions for the relevant observable quantities are
found in accurate agreement with exact numerical results. Under pulsed
excitation, the unequal time second order correlation function demonstrates the
triggered probabilistic generation of single photons well separated in time.Comment: Submitte
Obstacle Numbers of Planar Graphs
Given finitely many connected polygonal obstacles in the
plane and a set of points in general position and not in any obstacle, the
{\em visibility graph} of with obstacles is the (geometric)
graph with vertex set , where two vertices are adjacent if the straight line
segment joining them intersects no obstacle. The obstacle number of a graph
is the smallest integer such that is the visibility graph of a set of
points with obstacles. If is planar, we define the planar obstacle
number of by further requiring that the visibility graph has no crossing
edges (hence that it is a planar geometric drawing of ). In this paper, we
prove that the maximum planar obstacle number of a planar graph of order is
, the maximum being attained (in particular) by maximal bipartite planar
graphs. This displays a significant difference with the standard obstacle
number, as we prove that the obstacle number of every bipartite planar graph
(and more generally in the class PURE-2-DIR of intersection graphs of straight
line segments in two directions) of order at least is .Comment: Appears in the Proceedings of the 25th International Symposium on
Graph Drawing and Network Visualization (GD 2017
Scaling of spectral anisotropy with magnetic field strength in decaying magnetohydrodynamic turbulence
Space plasmameasurements,laboratory experiments, and simulations have shown that magnetohydrodynamic(MHD)turbulence exhibits a dynamical tendency towards spectral anisotropy given a sufficiently strong background magnetic field. Here the undriven decaying initial-value problem for homogeneous MHDturbulence is examined with the purpose of characterizing the variation of spectral anisotropy of the turbulent fluctuations with magnetic field strength. Numerical results for both incompressible and compressible MHD are presented. A simple model for the scaling of this spectral anisotropy as a function of the fluctuating magnetic field over total magnetic field is offered. The arguments are based on ideas from reduced MHD (RMHD) dynamics and resonant driving of certain non-RMHD modes. The results suggest physical bases for explaining variations of the anisotropy with compressibility, Reynolds numbers, and spectral width of the (isotropic) initial conditions
A quasi-analytical model for energy-delay-reliability tradeoff studies during write operations in perpendicular STT-RAM cell
One of the biggest challenges the current STT-RAM industry faces is
maintaining a high thermal stability while trying to switch within a given
voltage pulse and energy cost. In this paper, we present a physics based
analytical model that uses a modified Simmons' tunneling expression to capture
the spin dependent tunneling in a magnetic tunnel junction(MTJ). Coupled with
an analytical derivation of the critical switching current based on the
Landau-Lifshitz-Gilbert equation, and the write error rate derived from a
solution to the Fokker-Planck equation, this model provides us a quick estimate
of the energydelay- reliability tradeoffs in perpendicular STTRAMs due to
thermal fluctuations. In other words, the model provides a simple way to
calculate the energy consumed during a write operation that ensures a certain
error rate and delay time, while being numerically far less intensive than a
full-fledged stochastic calculation. We calculate the worst case energy
consumption during anti-parallel (AP) to parallel (P) and P to AP switchings
and quantify how increasing the anisotropy field HK and lowering the saturation
magnetization MS, can significantly reduce the energy consumption. A case study
on how manufacturing variations of the MTJ cell can affect the energy
consumption and delay is also reported.Comment: 6 pages, 9 figure
A Characterization of Visibility Graphs for Pseudo-Polygons
In this paper, we give a characterization of the visibility graphs of
pseudo-polygons. We first identify some key combinatorial properties of
pseudo-polygons, and we then give a set of five necessary conditions based off
our identified properties. We then prove that these necessary conditions are
also sufficient via a reduction to a characterization of vertex-edge visibility
graphs given by O'Rourke and Streinu
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